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United States Patent | 6,115,490 |
Platsch | September 5, 2000 |
To generate a high-contrast image of powder particles located on the surface of a print product, a measurement apparatus has an illumination unit which generates a measurement light beam which strikes the surface of the print product at glancing incidence. A measurement optics has an axis vertical to the surface of the print product and a diaphragm body is arranged in its focal point on the image side. The measurement optics forms an image of a surface region of the dusted print product on an image converter. An electronic evaluation unit determines the number and size of the powder particles from the image obtained on the image converter.
Inventors: | Platsch; Hans (Kupferstr. 40, D-70565 Stuttgart, DE) |
Appl. No.: | 952532 |
Filed: | December 29, 1997 |
PCT Filed: | April 22, 1996 |
PCT NO: | PCT/EP96/01680 |
371 Date: | December 29, 1997 |
102(e) Date: | December 29, 1997 |
PCT PUB.NO.: | WO96/35939 |
PCT PUB. Date: | November 14, 1996 |
May 07, 1995[DE] | 195 16 188 |
Current U.S. Class: | 382/141; 250/559.46; 348/128; 356/225; 382/108; 382/144; 382/192; 382/321 |
Intern'l Class: | G06K 009/00 |
Field of Search: | 382/108,112,144,145,149,192 250/559.46,564 356/138,218,225,237,338,339,340,375,376,400,431,141.3,141.2,141.4 348/86,125,128 |
4568188 | Feb., 1986 | Weber | 356/225. |
4660980 | Apr., 1987 | Takabayashi et al. | 356/345. |
4974261 | Nov., 1990 | Nakahara et al. | 382/192. |
5274713 | Dec., 1993 | Chang et al. | 250/559. |
5301244 | Apr., 1994 | Parulski | 382/59. |
5317380 | May., 1994 | Allemand | 356/338. |
5608817 | Mar., 1997 | Yamaoka et al. | 382/141. |
5680473 | Oct., 1997 | Kanzaka et al. | 348/128. |
5715052 | Feb., 1998 | Fujino et al. | 356/237. |
5907405 | May., 1999 | Mizutani et al. | 356/399. |